We have organized a Geriatric Anesthesia Research Center within the Department of Anesthesia of the University of Pennsylvania, wherein preoperative, intraoperative and postoperative measurements can be made, in rigorous fashion, of pertinent aspects of cardiopulmonary physiology considered germane to the evaluation and therapy of the older patient. This is not to be a service unit. We intend to capitalize on the opportunity for investigation that modern anesthetic care provides. Firstly, major risks in cardiopulmonary studies involve arterial and central venous catheterizations. The patients we propose to study will have such monitors placed as part of the usual pre-anesthetic preparation. Secondly, the stresses of anesthesia, surgery, and recovery will offer opportunity to evaluate functional status and reserve in ways that would not be attempted in ordinary elderly patients. Modern anesthesia dictates a variety of monitoring methods, some invasive. We simply plan to capitalize on this already indicated monitoring to elucidate functional reserve, control, and response. We will measure cardiac output, circulatory pressures, pulmonary volume, and ventilation, efficiency of gas exchange and other pertinent data in patients in the sixth through ninth decade, before, during and after the stress of anesthesia and operation. Control mechanisms will be studied by deliberate changes in blood gases, O2 and CO2. Extant methods will be modified for use in the unconscious elderly to permit eventual description of aging, and of the aged response to anesthesia.